Beyond Vascular Territories: The Dual Pathology of Posterior Cerebral Artery Stroke With Reversible Cytotoxic Splenial Lesion

The authors present a case highlighting an important stroke mimic: a cytotoxic lesion of the corpus callosum (CLOCC).This case report describes a 28-year-old male with pre-existing hypertension, poorly controlled type 2 diabetes, high BMI, and multiple atherosclerotic risk factors, including polysubstance use (cannabis, cigarettes, vaping), who presented with acute-onset left-sided weakness, blurred vision, and paraesthesia.Initial non-contrast CT head was unremarkable.Subsequent MRI demonstrated acute signal changes involving the splenium of the corpus callosum and the tail of the right hippocampus.CT angiography revealed an occlusion of the right posterior cerebral artery at the P2 segment; however, the atypical location for conventional ischaemia raised suspicion for an alternative or concurrent cytotoxic aetiology.Given the patient's markedly poor glycaemic control, a metabolic trigger was strongly considered.Serial MRI imaging was performed, and further supported this hypothesis by demonstrating near-complete regression of the abnormal signal within the splenium following glycaemic optimisation, whilst also correlating with clinical improvement.Management comprised dual anti-platelet therapy, strict glucose and blood pressure control, and lifestyle modification.This case underscores the importance of considering metabolic and cytotoxic aetiologies alongside conventional ischaemia in young stroke presentations, particularly where imaging findings are atypical for vascular territory.It highlights the diagnostic complexity of acute neurological presentations in young patients with significant vascular and metabolic risk factors, demonstrating how severe hyperglycaemia can mimic or coexist with acute ischaemic stroke.Atypical MRI findings for a PCA occlusion seen in this case emphasise the importance of considering reversible cytotoxic lesions, such as CLOCCs, as a differential diagnosis.